The present invention relates generally to ultrasonic imaging systems, and in particular to a sector scan ultrasonic imaging system which is of compact design and small power consumption.
In sector scan ultrasonic imaging systems which have hitherto been known in the art, a transmitter circuit is provided for each element of the transducer array and includes a programmable counter and a pulse generator connected thereto. The programmable counter of each transmitter circuit is so present that it generates an output at a predetermined delay time with respect to the output of other transmitter circuits so that the main beam transmitted from the transducer array is deflected at an angle to the longitudinal of the array. Each counter is preset by delay time data stored in a memory provided for each transmitter circuit, and the data is so selected that the main ultrasonic beam is angle incremented to scan across a sector field. Each programmable counter is supplied with high clock rate rectangular pulses of less than 10-nanosecond duration to generate an enabling signal for the associated pulse generator when the preset count value is reached. When enabled the pulse generator drives the associated piezoelectric element of the array to cause it to transmit an ultrasonic pulse into a subject body under investigation. One disadvantage of the prior art system, however, is that because of the short-duration pulses with which each programmable counter is driven, the power consumption of the counters is considerable which imposes space limitations on the structural design. The space limitations are further imposed by the necessity of providing a pulse generator for each transmitter circuit.